Vessel Impacts
Florida Keys

manatee with boat propellor scars
West Indian Manatee with boat propellor scars. Credit: USGS Sirenia Project

Why is it a concern?

Visitors, scientists, fishermen, commercial shippers, and other stakeholders of the Florida Keys National Marine Sanctuary (FKNMS) access the sanctuary through the use of recreational and commercial vessels. These vessels are an important part of the “blue economy” and also provide a safe way for many visitors to experience some of the sanctuaries most iconic places. However, there are several impacts from vessels that can impact biological and archaeological resources within the sanctuary. These impacts include ship strikes, ship groundings, lost containers from shipping vessels, and discharge of waste water and other materials.

Ship strikes pose a threat to marine mammals (such as dolphins and manatees) and sea turtles. Manatees in the sanctuary typically have boat propeller scars along their backs which is indicative of ship strikes. Seagrass and coral injuries from vessel groundings in the sanctuary typically include a combination of different injury types; seagrass beds can have propeller scars, berms, and blowholes, whereas coral reefs can have fragmented or crushed colonies, framework destruction, and blowholes. Prevention and restoration of seagrass and coral injuries represents an important step in reducing the cumulative impact of ship strikes throughout the sanctuary and in preserving this important ecosystem.

Vessels can also introduce unwanted contaminants and waste water into sanctuary waters. The most common and chronic form of spill is from small boat engine operations and usually involves small discharges of fuel, oil, or hydraulic fluid. Other small spills tend to be associated with oil and fuel discharges due to small vessel (<65 feet or 20 meters) groundings or sinkings. More research related to ship strikes, ship groundings, and vessel discharge could help to prevent impacts to sanctuary resources in the future.

Overview of Research

Research conducted by Sanctuary scientists and partners provides critical information to address existing and emerging resource conservation and management issues. The Overview of Research highlights some, but not necessarily all, of the research activities completed or ongoing at the Sanctuary.

grounded vessel
Vessel groundings can damage coral reefs and leave fragmented or crushed colonies. Credit: FKNMS, NOAA

Science Needs and Questions

The best available science is used by Sanctuary scientists and managers working to address priority resource conservation and management issues. As priorities change and new issues emerge, each Sanctuary develops new science needs and questions and works with partners to address them.

  • How do marine mammals and sea turtles use the water column spatially and temporally and how can this information inform policies to mitigate collisions between marine organisms and ships?
  • How do marine mammals and sea turtles react to the approach of vessels and how can this information inform policies to mitigate collisions?
  • When are marine mammals and sea turtles most abundant within the sanctuary boundaries and how can this information inform policies to mitigate the risk of ship strikes?
  • Investigate efficacy of ATONs relative to vessel grounding locations and rates.
  • Can boater education courses decrease the likelihood of vessel groundings or marine life strikes?
  • Are there better ways to restore seagrass beds and coral reefs after vessel groundings?
  • Are there critical data gaps in current habitat equivalency analysis tools?

Education and Outreach Material

Please refer to the Florida Keys National Marine Sanctuary website to learn more about education and outreach materials.


Hallac, David E., et al. "Boating impacts to seagrass in Florida Bay, Everglades National Park, Florida, USA: links with physical and visitor-use factors and implications for management." Marine and Freshwater Research 63.11 (2012): 1117-1128.

Laist, David W., and Cameron Shaw. "Preliminary evidence that boat speed restrictions reduce deaths of Florida manatees." Marine Mammal Science 22.2 (2006): 472.

“Scarring of Florida's seagrasses: Assessment and Management Options”. Florida Marine Research Institute Technical Report TR-1.